The present invention generally relates to a storage management system and hierarchy management method for arranging, in the appropriate hierarchy at the appropriate timing, data in arrangement units represented by, for example, a volume or a volume segment based on the characteristic of a server job that makes use of storage in a hierarchical storage.
Lowering the cost of storage management has become a challenge in recent years in line with the growing quantities of data handled by companies. The implementation of hierarchy management is advancing as a procedure for reducing storage management costs. This hierarchy management is technology that combines expensive, high-speed disks with inexpensive, low-speed disks to configure a SAN (Storage Area Network), and rearranges data in accordance with the data access frequency.
In the technology disclosed in Japanese Patent Application Laid-open No. 2000-293317, a storage apparatus measures the access frequency for each volume accessed from a business server, and displays the measurement result to the storage administrator. Further, in the technology disclosed in Japanese Patent Application Laid-open No. 2000-293317, the storage apparatus migrates data stored in a volume from a first disk device to a second disk device based on an instruction from the storage administrator. Also, Japanese Patent Application Laid-open No. 2007-066259 discloses that access frequency measurements are performed for each segment of a volume.
In the hierarchy management represented in Japanese Patent Application Laid-open No. 2000-293317 and Japanese Patent Application Laid-open No. 2007-066259, it becomes possible for the storage apparatus administrator to effectively make proper use of high-speed disks and low-speed disks by rearranging a high-access-frequency volume in a high-speed disk and a low-access-frequency volume on a low-speed disk based on an access frequency measured in either the storage apparatus or in a server that issues an I/O request (for example, a read request or a write request).
Further, Japanese Patent Application Laid-open No. 2003-216460 discloses the realization of hierarchy management by carrying out rearrangement based not only on the access frequency of the past as disclosed in Japanese Patent Application Laid-open No. 2000-293317, but also on the result of a prediction that predicts the access frequency that will occur in the future based on an access cycle.
In this specification, a volume and a volume segment, which constitute the rearrangement target, are generically called the arrangement unit.